Jar



R. P. FISHER Dec. 31, 1935.

INVENTOR. ROBER T R FISHER K \J- M Filed Dec. 28, 1933 ATTORNEY.

UNITED STATES Patented Dec. 31, 1935 JAR Application December 28, 1933, Serial No. 704,265

7 Claims. (01. 255-27) ATENT OFFICE This invention is a jar for loosening a well drilling tool when it is stuck in a well bore; and has for its object to provide an engagement between -relatively telescopic parts, inoperative during contraction of. the telescopic parts but then operative for arresting expansion of the parts, with the arresting means adapted to yield when an appreciable strain is exerted on the tool, and thereby suddenly releasing the telescopic parts for relative expansion terminating in their abrupt impingement to produce a jarring action.

It is a further object of the invention to adapt a roller for inoperative retraction and operative projection during contraction and expansion of the telescopic parts, with the operatively projected roller engaging a cooperating abutment for arresting expansion of the telescopic parts, and the abutment adapted to yield responsive to appreciable strain on the tool, for disengaging the abutment from the roller and thereby releasing the telescopic parts for sudden expansion and abrupt impingement.

It is a still further object of the invention to make multi-point contact with the yieldable abutment when arresting relative expansion of the telescopic parts, with yielding of the abutment responsive to strain on the tool adapted to simultaneously. disengage the plurality of. contacts for suddenly releasing the telescopic parts for jarring impact.

It is a still further object of the invention to adjust the abutment so that it will yield responsive to any desired strain, thereby permitting ready adjustment of the blow which is struck by the ar.

Further objects of the invention will be readily understood from the following description of the accompanying drawing, in which:

Fig. 1 is a side elevation, partly in-axial section, showing the relative position of the parts during setting of. the jar.

Fig. 2 is a similar view showing the jar set and ready for operation responsive to strain exerted on the tool,

Figs. 3 and 4 are transverse sections on the lines 33 and 4-4 respectively of Fig. l.

The jar comprises a relatively telescopic mandrel l and body 2 adapted for incorporation in a drill string 3, as for example by subs 4-5 respectively projecting upwardly from the mandrel and depending from the body. The mandrel has a head 6 adapted to strike a shoulder 1 in the bore of the body for imparting a jarring blow, and the mandrel and body are free to telescope but are fixed against relative rotation, as for example by a spline 8. The mandrel preferably has a circulation bore 9 communicating at its upper end with the bore of the upper portion of the drill string 3, and a wash pipe preferably depends from the bore of the mandrel and is packedoff as shown at l I, and is slidable in a circulation bore i2 which extends through the sub 5 for communication with the bore of the lower portion'of the drill string.

The mandrel has engaging means cooperating 10 with a yieldable abutment in the bore of the body, and while the mandrel is being telescoped into the body the engaging means is automatically retracted so as to clear the cooperating abutment, but when the mandrel has been telescoped the engaging means is automatically projected for engaging the cooperating abutment, thereby arresting elevation of the mandrel until such strain is exerted thereon as will cause the abutment to yield, whereupon the mandrel is released for sudden upward movements resulting in impingement of its head 6 against the shoulder i, and thereby imparting a jarring blow to the v drill string.

For this purpose a roller is journaled in the side of the mandrel below its head 6, and a spring arm which is mounted in the body 2 has an abutment adapted for engagement by the roller. The roller engages the abutment and is forced back into its bearing groove so as .to clear the abutment to permit telescoping of the mandrel into the body, but when the mandrel has been lowered until the roller is below the abutment the roller is moved outwardly in its groove by gravity, so that when the mandrel is subsequently elevated relative to the body the roller engages the abutment and arrests elevation of the mandrel until such strain is exerted on the drill string as will cause the spring arm to yield for retracting its abutment so as to clear the roller and release the mandrel.

A plurality of rollers are preferably employed, with an abutment cooperating with each roller so as to provide a multi-point contact, and the abutments are adapted to yield so as to simultaneously disengage the rollers and thus assure sudden release of the mandrel for striking a sharp jarring blow.

As an instance of this arrangement the mandrel has an enlargement I5 below the head 6, and the enlargement tapers downwardly so that it has opposite inclined sides. A plurality of vertically spaced transverse grooves l6 are formed in each of these opposite sides of the enlargement. A roller I1 is journaled in each of the grooves, and the grooves open downwardly and outwardly through the inclined sides of the enlargement and are of a depth permitting the rollers to be contracted within the grooves as shown at Fig. 1, or permitting gravity projection of the rollers from the grooves as shown at Fig. 2. Projection of the rollers is limited, as for example by plates l8 which are fixed on the enlargement l and which havelips ii! at their side edges overlying the ends of the rollers as shown at Fig. 4.

A spring arm cooperates with the rollers at each of the opposite inclined sides of the enlargebore of the body at the shoulder 1. Each spring arm has an enlargement 22 inclined parallel to the proximate inclined side of enlargement l5, and the enlargement 22 has a plurality of vertically spaced transverse recesses 22 forming abutments 23 therebetween, one for each of the rollers l1 and having their lower abutment faces inclined asshown at 24. The spring arms are normallypositioned so that their abutments 23 will just clear the proximate inclined sides of enlargement l5, and for this purpose the lower ends .of the spring arms may extend into a collar 25 which is received in the lower end of the body 2. g

In operation, when the lower portion of drill string 3 is stuck in a Well bore, the upperportion of the drill string is lowered relative thereto so as to telescope the mandrel l in the body 2. The rollers I! thus engage the tapering surfaces of enlargements 22 and are forced 'backwardly and upwardly into their grooves it as shown at Fig. 1, so that the mandrel may be lowered until the rollers are opposite the respective cooperating recesses. 22. The rollers then gravitate downward- ;ly and outwardly for projection from their grooves, and in this position the jar is set, ready for operation.

An upward strain is then exerted on the upper portion of the drill string so that the projected rollers engage abutments 23 for arresting elevation of the mandrel is shown at Fig. 2; and the upward strainis continued until the spring arms 20 yield andbow outwardly, thereby disengaging the abutments from the rollers so that the mandrel is suddenly released for abrupt elevation by the upward strain exerted thereon. The head 5 thus strikes a sharp blow against the, shoulder l for jarring thegdrill string.

The force of the jarring blow may be adjusted by tensioning the spring arms 20 so that they will yield and release the mandrel when any desired strain has been exerted on the drill string. For this purpose the ends of the spring arms which are received in the collar'25 may be inclined as shown at 30, and the bore of the collar is correspondingly tapered as shown at 3|. The collar is adapted for longitudinal adjustment relative to body 2, as for example by a threaded connection 33, and the end of the collar preferably has slots 32 adapted for engagement by a suitable tool for rotating the collar to adjust the same. Adjustment of the collar wedges its tapering bore over the inclined ends of arms 20, andthe spring arms may thus be contracted for tensioning them to a degree which will necessitate a predetermined strain upon the drill string before the abutments 23 disengage the rollers 11 soas to operatethe jar.

The invention thus provides a jar which may be readilyset as a result of therollers contracting within their grooves I6, with the rollers then automatically projected and engaging the abutments 23 for arresting elevation of the mandrel, and the abutments adapted to yield responsive to a predetermined strain so that the rollers 5 clear the abutments and thereby suddenly release the mandrel for striking a jarring blow against the cooperating shoulder of the body.

I claim:

1. In a jar, relatively telescopic elements, 00- operating members on said elements adapted for engagement for retracting one of said members within its telescopic element to permit the cooperating members to clear one another for relative contraction of the telescopic elements, said one of the members being adapted for gravity projection relative to its telescopic element when the telescopic elements have been relatively contracted, so that the cooperating members are adapted for engagement responsive to strain tending to relatively expandthe telescoped elements, with said engagement arresting relative expansionof the telescoped elements, the other of said engaging members being adapted to yield responsive to predetermined strain, for releasing the engagement between the members to permit relative expansion of the telescopic elements, and cooperating means on the telescopic elements for limiting their relative expansion so as to produce ajarring action by impact of said cooperating means.

2..In a jar, relatively telescopic elements,

. members on said elements each having vertically spaced projections, the projections of one of said members comprising vertically spaced transverse rollers, the projections of the other of said members comprisingvertically spaced abutments, the projections of said members being adapted to clear one another for relative contraction of the telescopic elements, the projections of said members being adapted for engagement responsive to strain tending to relatively expand the telescoped elements, with said engagement arresting relative expansion of the telescoped elements, the engaging members being adapted for relative yielding responsive to predetermined strain, for releasing the engagement between the members to permit relative expansion of the telescopic elements, and cooperating means on the telescopic elements for limiting their relative expansion so as to produce a jarring action by impact of said cooperating means.

3. In a jar, relatively telescopic elements one of said elements having atransverse groove opening downwardly and outwardly, a roller journaledin-the groove, a projection on the other of the telescopic elements, the roller being adapted for engagement by the projection for retracting the roller in its groove to permit the rollerand projection to clear one another for relative contraction of the telescopic elements, the roller after passing the projection being adapted .to gravitate in its groove for projection therebeyond so as to engage the projection responsive to strain tending to relatively expand the telescoped elements, with said engagement arresting relative expansion'of the telescopedelements,the projectionbeing adapted to yield responsive to predetermined strain,- for ,releasing the engagement between the roller and projection to permit relativev expansion of the telescopic elements, and cooperating means on the telescopic elements for limiting; their relative expansion so as to produce a jarring action by impact of said cooperating means.

4. In a jar, relatively telescopic elements, a spring arm carried by one of said elements, a projection on the spring arm, a cooperating projection on the other telescopic element, said projections being adapted for engagement for retracting the second mentioned projection within its telescopic element to permit the cooperating projections to clear one another for relative contraction of the telescopic elements, the second mentioned projection being adapted for gravity projection relative to its telescopic element when the telescopic elements have been relatively contracted, so that the cooperating projections are adapted for engagement responsive to strain tending to relatively expand the telescopic elements, with said engagement arresting relative expansion of the telescoped elements, the spring arm being adapted to yield responsive to predetermined strain, for disengaging its projection from the cooperating projection to permitrelative expansion of the telescopic elements, and cooperating means on the telescopic elements for limiting their relative expansion so as to produce a jarring action by impact of said cooperating means.

5. In a jar, relatively telescopic elements, one of said elements having a plurality of vertically spaced transverse grooves opening downwardly and outwardly, a roller journaled in each of the grooves, a spring arm fixed at its ends to the other telescopic element and having a plurality of vertically spaced projections, the rollers being adapted for engagement by the respective projections for retracting the rollers in their grooves to permit the rollers and projections to clear one another for relative contraction of the telescopic elements, the rollers after passing the corresponding projections being adapted to gravitate in their grooves for projection therebeyond so as to engage the corresponding projections responsive to strain tending to relatively expand the telescoped elements, with said engagement arresting relative expansion of the telescoped elements, the spring arm being adapted to bow medially of its ends responsive to predetermined strain, for disengaging the projections from the cooperating rollers to permit relative expansion of the telescopic elements, and cooperating means on the telescopic elements for limiting their relative expansion so as to produce a jarring action by impact of said cooperating means.

6. In a jar, relatively telescopic elements, members on said elements each having vertically spaced projections, the series of projections of each member being inclined to the vertical with the series of projections of the two members 5 parallel, whereby the series of projections of the first member are adapted to simultaneously engage the series of projections of the second member for retracting the projections of the first member within said member to permit the series of projections of the members to clear one another for relative contraction of the telescopic elements, the series of projections of the members being adapted for engagement responsive to strain tending to relatively expand the tele- 15 scoped elements, with said engagement arresting relative expansion of the telescoped elements, the series .of projections of the second member being adapted to yield responsive to predetermined strain, for simultaneously disengaging the series 2 of projections of the second member from the series of projections of the first member to permit relative expansion of the telescopic elements, and cooperating means on the telescopic elements for limiting their relative expansion so as to pro- 25 duce a jarring action by impact of said cooperating means.

7. In a jar, relatively telescopic elements, one of said elements having a transverse groove opening downwardly and outwardly, an abutment 30 movable in the groove, a projection on the other of the telescopic elements, the abutment being adapted for engagement by the projection for retracting the abutment in its groove against the force of gravity to permit the abutment and pro- 5 jection to clear one another for relative contraction of the telescopic elements, the abutment after passing the projection being adapted to gravitate in its groove for projection therebeyond so as to engage the projection responsive 40 to strain tending to relatively expand the telescoped elements, with said engagement arresting relative expansion of the telescoped elements, the projection being adapted to yield responsive to predetermined strain, for releasing the engagement between the abutment and projection to permit relative expansion of the telescopic elements, and cooperating means on the telescopic elements for limiting their relative expansion so as to produce a jarring action by impact of said cooperating means.

ROBERT P. FISHER. 

